High-frequency inductor



Feb. 17, 1953 M. R. HUBBARD 2629081 HIGH-FREQUENCY INDUCTOR Filed April 26. 1950 OUTPUT [/VPUT INVENTOR. Mf'ALE' Raf/[155A R0 A Morney Patented Feb. 17, 1953 2,629,081 "HIGH-FREQUENCY INDUCTOR Merle R. Hubbard, Cedar Rapids, Iowa, assignor to Collins Radio Company, Cedar Rapids, Iowa, I

a corporation of Iowa Application April 26, 1950, Serial No. 158,225

3 Claims. (-01. 336- 137) This invention relates in general to a high frequency tuner and in particular to a variable inductor.

In the field of electronics, higher and higher frequencies are being used, and it becomes in-' creasingly difiicult to obtain capacitances and inductances as the frequency-is increased. At times it is desirable to have tunable inductors at these high frequencies.

polystyrene "or other insulating "material. 'The wedge shaped member26 is-formed witha pair-of slots 27 and 28 which receives therein pins 29 that are attached to the shorting bars l6 and I1,

respectively.

As the thumb screw 24 is rotated -i-t"m"ove's the threaded shaft 23 longitudinally-of the pillar 2| It is an object of this invention, therefore, to 21 and 28 determine the motion impartedto' the provided a variable inductor which may be used at bars It and I1, and variations the shape of high frequencies the slot change the characteristics *of the tu'ner. 1

Another object of this invention is to provide a A variable condenser is connected across the piltunable inductor which may be varied in a predelars II and I2 and comprises, as best shown in termined man Figure 2, the thumb screws 3! and 32 which pass Yet another object of this invention is to protra ve sely through the p s H and I2 to vide a tuned circuit which may have its resonant ter nate in condenser plates 33 and 34, respecfrequency varied linearly with respect to the rotively. Adjustment of the distance between the tation of a shaft, plates 33 and 34 varies the capacitance in a well A feature of this invention is found in the proknown manner. vision for a pair of bars rigidly mounted to sup- Figure 2 illustrates the tuner of this invention porting means at one end, and movable relative Showing its us as a filter- An put cable 36 has to each other along a common shorting bar at the its center conductor connected between two confree d densers C1 and C2. The opposite side of C1 is Further objects, features, and advantages of 5 connected to ground. The opposite side of C2 is this invention will become apparent from the connected t the p ar l2. Capacitors C4. and C5 following description and claims when read in are connected in series between the pillar II and i of th d i i whi h; ground and an output cable 31 is connected be- Figure 1 is a perspective view of the variable tween condensers C4 and C5. As the position of tuned circuit of this invention, and; the bars [8 and I1 is adjusted for a particular Figure 2 is a schematic diagram of the apparafrequency, the output from 31 will contain the ,tus'of Figure 1 illustrating the various electrical resonant frequency of the tuner. The condenser connections. C3 may be adjusted to vary the tuning range.

Figure 1 shows a base member [0 made of in- The apparatus will have a high Q. sulating material, for example, Bakelite. A pair 5 The applicant has built and tested a tuner 0f p y extending p H and I2 P which may be adjusted over the range from 100 t v y, a mounted adja One end of the plate to 400 megacycles, and very linear results have It) by suitable hold means for example, been obtained when frequency is potted against Screws, not ShOWn- Posts I l and may be made angular position of the shaft 23. Applicant used from conducting material as, for example, copper. 40 bars and H which are about two inches in Attached to the pO II and are a P of length and have a diameter of approximately flexible Conducting members and '4. Attached of an inch The values for the condensers areto the free end of the support members 13 and M are a pair of conducting bars or rods l8 and C1 40 rPlcronfncrofamds n. Slide contacts 18 and I9 are attached to the 4 nilcromlcrofereds free end of each bar. A third upright post 2 C3var1able between 0.3-2.0 micromicrofarads is connected to the opposite end of the plate Ill C4 2 mlqromlqrofamds and has a crescent shaped shorting bar 22 atmlcmmlcrofarads tached thereto. The sho t b 2 might be It is seen that this invention provides means for of copper. The slide contacts 18 and I9 slidably 5o obtaining a variable tuner which may have a engage the shorting bar 22. A shaft 23 is threadlinear tuning chaarcteristic over a relatively wide edly received through the post 2 I and has a thumb ba screw 24 attached to O e e d t The 1 Although this invention has been described with posite end of the shaft 23 is rotatably attached to respect to particular embodiments thereof, it is a wedge shaped member 26 which may be made of not to be so limited as changes and modifications may be made therein which are within the full intended scope, as defined by the appended claims.

I claim:

1. A high frequency tunable circuit comprising, a first post, a second post, a first conducting rod connected to said first post, a second conducting rod connected to said second post, a third post, a shorting bar attached to said third post and engaging the ends of the first and second conducting rods, a shaft threadedly received through said third post, a wedge shaped member rotatably supported at one end of said shaft, a pair of slots formed in said wedge shaped member, downwardly extending pins connected to each of said rods and received in said slots, and means for rotating said shaft to vary the inductance of the tuner.

2. A high frequency tunable circuit comprising an insulated base member, a first upright electrically conducting post mounted on said base member, a second electrically conducting post mounted adjacent the first post on the base member. a first flexible electrical conducting means attached to said first post, second flexible electrically conducting means connected to the second post, a first electrically conducting rod connected to the first flexible means, a second electrically conducting rod connected to the second flexible means, a third post mounted to the base member, a crescent-shaped electrically conducting shorting bar attached to said third post, and the ends of the first and second conducting rods farthest from the flexible members slidably en gageable with the shorting bar.

3. A high frequency variable tuner according to claim 2 wherein the third post supports a threaded shaft therethrough, an electrically insulating wedge-shaped member mounted to the end of said threaded shaft, first transverse means atached to the first rod and engageable with a first slot formed in said wedge member, second transverse means attached to the second rod and engageable in a second slot formed in the wedgeshaped member, and means for turning said threaded shaft to vary the distance between said rods.

MERLE R. HUBBARD.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 926,934 De Forest July 6, 1909 2,382,435 Mann et al Aug. 14, 1945 2,384,504 Thias Sept. 11, 1945 2,445,700 Vaughan July 20, 1948 2,446,003 Gardiner July 27, 1948 2,453,994 Lappin et al Nov. 16, 1948 2,467,737 Germer Apr. 19, 1949 2,491,480 Davis et a1 Dec. 20, 1949 2,510,272 Arnett June 6, 1950 

